In today’s oceans, sea turtles, marine iguanas, saltwater crocodiles and sea snakes are the main reptilian inhabitants, among tons of mammals and fish. This wasn’t always the case, and fossil evidence shows that around 252 million years ago, reptiles dominated the seas. Now, an international team of scientists has put together another piece of the puzzle, identifying the oldest known marine reptile fossil in the Southern Hemisphere. The vertebrate fossil belongs to a sea dragon-like nothosaurus and was discovered in a riverbed on New Zealand’s South Island. The discovery comes as The study was published in the journal Nature on June 17th. Current Biology.
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When reptiles ruled the seas
Millions of years before dinosaurs roamed the Earth, reptiles were kings of Earth’s oceans.
The most diverse and geologically longest surviving group of extinct marine reptiles is Dragon-finned fishTheir evolutionary history spans more than 180 million years. Plesiosaurus with a long neckIt resembled the popular image of the Loch Ness Monster.
of Nothosaurus It was a distant ancestor of the plesiosaurs. Approximately 23 feet long And used Four paddle-like limbs It had a flattened skull for swimming and thin, conical teeth in its mouth for catching fish and squid.
Nothosaurus vertebrae This study Its history dates back to when what is now New Zealand lay on the Antarctic coast of a vast super-ocean called Panthalassa. About 250 million years ago, when a mass extinction event called the Great Dying devastated marine ecosystems, surviving reptiles found a chance to live in the Earth’s oceans.
Scientists have provided evidence for this evolutionary criterion Arctic island of Spitsbergennorthwestern North America, and southwestern China. The nothosaurus vertebrae discovered in the study are among the latest discoveries from this period and may shed new light on the history of ancient marine reptiles in the Southern Hemisphere.
A new look at old fossils
The New Zealand nothosaurus Geological Survey of 1978It was embedded in a boulder in a stream at the base of Mount Harper on New Zealand’s South Island, and its significance was not fully realized until a team of paleontologists from Australia, Timor-Leste, Norway, New Zealand and Sweden worked together to examine and analyze the vertebrae and other fossils.
“The New Zealand nothosaurus is more than 40 million years older than the oldest sauropod fossil yet found in the Southern Hemisphere,” said study co-author Benjamin Keir, a paleontologist at the Museum of Evolution, Uppsala University, Sweden. It said in a statement“We show that these ancient marine reptiles lived in shallow coastal environments rich in marine life within the Antarctic Circle at that time.”
The oldest nothosaur fossils date to approximately 248 million years ago and are found primarily along an ancient low northern latitude belt that stretches from the far northeastern to northwestern boundaries of the Panthalassa superocean.
Surfing in the Panthalassa Ocean
Paleontologists are still Discuss The origin, distribution and time of Nothosaurus’ arrival in these remote regions are unknown, although some leading theories suggest that they may have migrated along Arctic coastlines, swam inland seas or used ocean currents to cross the ocean. Panthalassa Super OceanNow, this new nothosaurus fossil has poured cold water on these hypotheses.
“Using a time-calibrated evolutionary model of the global distribution of sauropods, we show that nothosaurs originated near the equator and then rapidly spread north and south, simultaneously with the re-establishment of complex marine ecosystems after the great extinction that marked the beginning of the Age of Dinosaurs,” Keir said.
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When the Age of the Dinosaurs began, Earth was going through a period of extreme global warming. Warmer temperatures allowed these marine reptiles to thrive in the Antarctic region of the Earth. Kear and team believe this means that the ancient polar regions were likely the main route for the first global migration of nothosaurs, which would have been incredibly long. Today’s whale migration.
Further research is needed to confirm this, and it will only be possible by unearthing more remains of this ancient, real sea dragon.
“There are no doubt fossils of long-extinct sea monsters still waiting to be discovered in New Zealand and elsewhere in the Southern Hemisphere,” Keir says.
